Rewrite depfile from sbox to stay reproducible

sbox will generate a random directory for the output root, and most
tools will encode that directory name in the output target of the
depfile.

So embed the library from dep_fixer into sbox so that it can rewrite the
output filename to a static (reproducible) value. Ninja doesn't care
what that value is, so it's just "outputfile".

Also fix up rule_builder to actually tell sbox about the depfile.

Test: mmma system/iorap; check the contents of:
out/soong/.intermediates/system/iorap/libiorap-binder/android_arm_armv7-a-neon_core_static/gen/aidl/system/iorap/binder/com/google/android/startop/iorap/IIorap.cpp.d

Change-Id: I3640a2e8b0c034f143a35e398a8418a6d621b265